The present invention is directed to integrated circuits and their processing for the manufacture of semiconductor devices. In particular, the invention provides a method and system for monitoring and controlling process related information for the manufacture of semiconductor integrated circuit devices. More particularly, the invention provides a method and system using a better or worse processes to monitoring and controlling process related information for the manufacture of semiconductor integrated circuit devices. But it would be recognized that the invention has a much broader range of applicability.
Integrated circuits have evolved from a handful of interconnected devices fabricated on a single chip of silicon to millions of devices. Conventional integrated circuits provide performance and complexity far beyond what was originally imagined. In order to achieve improvements in complexity and circuit density (i.e., the number of devices capable of being packed onto a given chip area), the size of the smallest device feature, also known as the device “geometry”, has become smaller with each generation of integrated circuits.
Increasing circuit density has not only improved the complexity and performance of integrated circuits but has also provided lower cost parts to the consumer. An integrated circuit or chip fabrication facility can cost hundreds of millions, or even billions, of U.S. dollars. Each fabrication facility will have a certain throughput of wafers, and each wafer will have a certain number of integrated circuits on it. Therefore, by making the individual devices of an integrated circuit smaller, more devices may be fabricated on each wafer, thus increasing the output of the fabrication facility. Making devices smaller is very challenging, as each process used in integrated fabrication has a limit. That is to say, a given process typically only works down to a certain feature size, and then either the process or the device layout needs to be changed. Additionally, as devices require faster and faster designs, process limitations exist with certain conventional processes, including monitoring techniques, materials, and even testing techniques.
An example of such processes include ways of monitoring process related functions during the manufacture of integrated circuits, commonly called semiconductor devices. Such monitoring processes often include use of meantime to failures, commonly called “MTTF,” among semiconductor devices produced with similar or the same process conditions and designs. As an example, a conventional test on comparing mean lives has been used to compare two different products, such as the MTTF of two Weibull distributions with equal shape parameters. However, two products with the same MTTF may have different reliabilities. In most cases, there is need to know if the reliability of two products are comparable. In such case, MTTF are not generally suitable indices because, even both products meet the lifetime requirement, the reliabilities may not be comparable. These and other limitations will be described in further detail throughout the present specification and more particularly below.
From the above, it is seen that an improved technique for manufacturing semiconductor devices is desired.